Addition Reactions Research Articles

Formation of the Interstellar Sugar Precursor, (Z)-1,2-Ethenediol, through Radical Reactions on Dust Grains

In recent years, the continued detection of complex organic molecules of prebiotic interest has refueled the interest in a panspermic origin of life. The prebiotic molecule glyceraldehyde is proposed to be formed from (Z)-1,2-ethenediol, a molecule recently detected toward the G+0.693-0.027 molecular cloud at the galactic center. In this work, we computationally simulate the formation of (Z)-1,2-ethenediol from vinyl alcohol on the surface of amorphous solid water in a two-step synthesis involving an OH addition and an H abstraction reaction. In total, we considered all reaction possibilities of the 1,1- and 1,2-OH addition to vinyl alcohol followed by H abstraction or H addition reactions on the resulting radicals. The combination of these reactions is capable of explaining the formation of (Z)-1,2-ethenediol provided a suprathermal diffusion of OH. We also conclude that our proposed formation pathway is not selective and also yields other abstraction and addition products. Key in our findings is the connection between the adsorption modes of the reactants and intermediates and the stereoselectivity of the reactions.

Exploring the ring-opening metathesis polymerization process by kinetic Monte Carlo simulation

Investigating the kinetics of polymerization reactions is a powerful tool to obtain information for the engineering design of such processes. It provides insights into how the relative rates of elementary reactions which influence both the kinetics of the reactions and thus characteristics of the products as well, particularly when the reaction parameters of these reactions are unknown. Among polymerization processes, ring-opening metathesis polymerization (ROMP) has gained broad academic and industrial interest, due to its mild conditions to obtain a wide range of polymer products. In this study, kinetic Monte Carlo simulation was applied to reveal the effect of the elementary reactions of ROMP on the kinetics and product distribution. Both the propagation and the cross-metathesis reactions were considered, with the latter leading to the formation of various types of macrospecies whose population levels were also monitored. Relevant tendencies were observed regarding how the variations in the reaction parameters of the elementary reactions of this polymerization process, such as reaction probabilities, monomer addition method, catalyst-to-monomer ratio, and reaction time, affect the kinetics of the polymerization process and the product distributions. These variations also influence the key macromolecular parameters of the resulting polymeric materials, including chain length distribution (CLD), population levels, and polymer functionalities. The results of this study indicate that this simulation technique is a valuable tool for mapping the tailoring possibilities of modifying the reaction parameters of ROMP to achieve desired properties. These properties include number average molecular weight, polydispersity, chain end functionality, and macrocycle-free products.

The effect of co-modification of ultrathin g-C3N4 nanosheets with Ag and S on photocatalytic hydrogen production

The technology of photocatalytic water splitting holds immense potential for hydrogen (H2) generation. However, its development is hindered by a lack of active sites and low efficiency of photogenerated carriers. In this study, Ag-S-CN ultrathin nanosheets were successfully fabricated by co-modification of graphitic carbon nitride (CN) with silver (Ag) and sulfur (S). S doping within the CN layers broadened light absorption and provided additional reaction sites, while the incorporation of Ag into the CN interlayers enhanced the migration rate of photogenerated carriers between adjacent layers via Ag-S bonds. Consequently, the 0.05 Ag-S-CN photocatalyst achieved a high H2 yield of 0.93 mmol g-1 h-1 without requiring any additional cocatalyst, which is approximately 23.25 and 10.33 times higher than that of CN and S-CN, respectively. This work presents an effective strategy for developing highly efficient photocatalysts.

An environmentally friendly and superhydrophobic melamine sponge self-roughened by in-situ controllably grown polydopamine nanoparticle for efficient oil-water separation

The preparation of conventional superhydrophobic sponges inevitably requires the involvement of noxious and non-degradable raw materials，thus threatening ecosystems. As reported herein, an environmentally friendly and superhydrophobic melamine sponge is facilely prepared for efficient oil-water separation, which is completely derived from eco-friendly substances. The formation of a hierarchical structure on the sponge skeleton was achieved via the in-situ controllable growth of polydopamine nanoparticles in mildly alkaline solution. In addition, octadecyl amines (ODA) with long chains of hydrophobic alkyl groups were grafted onto the polydopamine coating to reduce the surface energy through Schiff base or Michael addition reactions. Ultimately, the resulted sponge possessed extreme water repellency with a water contact angle (WCA) of 153.21 ± 1.31° and could retain its superhydrophobicity when it was exposed to solutions with different pH values and high temperature. Moreover, the resultant sponge exhibited fully reversible compressibility with up to 80% strain and excellent structural stability after 200 cyclic compression tests. Meanwhile, distinct organic liquid absorption experiments were conducted to confirm the resulted sponge with excellent oil absorption capacity (73.46 - 119.66g/g) and oil-water separation properties. Therefore, the as-prepared superhydrophobic sponge provides valuable insight into efficient oil-water separation.

Injectable self-healing alginate/PEG hydrogels cross-linked via thiol-Michael addition bonds for hemostasis and wound healing

In this study, an alginate/PEG hydrogel was developed via a thiol-Michael addition reaction between oxidized quinone of catechols on dopamine-grafted sodium alginate (SA-DA) and sulfhydryl groups of 4-arm polyethylene glycol tetra-thiol (4-arm PEG-SH) under mildly basic conditions. Through the formation of thiol-terminated catechol groups, the accompanying oxidized catechols are reduced, significantly strengthening the internal network structure of the hydrogel and improving tissue adhesion. Meanwhile, the hydrogels have excellent self-healing properties due to the dynamic non-covalent bonds between the groups. Adjustment of hydrogel properties by varying the mass ratio of two hydrogel precursors. Due to the high content of thiol-terminated catechol groups, the Gel 3 exhibited good tissue adhesion, rapid self-healing ability, and other multifunctions beneficial to wound healing, including killing of E. coli and S. aureus, rapid hemostasis and promoting migration of L929 cells. The full-thickness skin wound model shows that the hydrogel dressing significantly accelerated wound contraction, with increased granulation tissue thickness, collagen disposition, and enhanced vascularization, thus promoting wound healing. Therefore, the thiol-Michael addition reaction is an effective method for creating multifunctional hydrogels, and the injectable self-healing alginate/PEG hydrogels prepared in this way could be used in the biomedical area as wound healing dressing materials.

High strength “breathable” glycosilicone/Aloe vera polysaccharide-based gel dressing for efficient wound repair

Medical wound dressings are effective in protecting wounds, maintaining moisture, creating an optimal healing environment and accelerating wound healing. However, their deficiencies in mechanical properties, adhesion and prevention of adhesion to the wound bed have been identified as limiting factors for their therapeutic efficacy in wound healing. To address these issues, we prepared glycosilicone gel dressings consisting of hydrophobic polysiloxanes and highly hydrophilic polysaccharides via ester exchange and silicone hydrogen addition reactions. Silicone gel dressings exhibit skin-like “respiratory” properties, with good permeability to O2 and CO2. Additionally, elongation and other important parameters are similar to those of the skin, which provides a foundation for the application of silicone gels in the field of wound dressings. The introduction of Aloe vera polysaccharide (AP) results in the glycosilicone gel exhibiting certain mechanical properties, including a tensile strength of 0.35 MPa and an adhesion force of 10 N/m. Furthermore, a mouse model of total skin defect demonstrated that the wound healing rate of the mice on the 12th day was 98 %, which effectively promotes wound healing. Consequently, the glycosilicone gel is anticipated to be an optimal wound dressing.

Rational design of an ultrabright quinolinium-fused rhodamine turn-on fluorescent probe for highly sensitive detection of SO2 derivatives: Applications in food safety and bioimaging

Sulfur dioxide (SO2) is an essential signaling molecule involved in various physiological processes within living organisms. Bisulfite (HSO3−) possesses antioxidant, antimicrobial, and preservative properties, making it a common food additive. However, elevated levels of SO2 or excessive HSO3− intake can lead to a range of diseases, highlighting the importance of detecting SO2 and its derivatives (HSO3−/SO32−). This study presents a quinolinium-fused rhodamine fluorogenic probe (RQB-R) for ultrafast, highly selective, and sensitive detection of HSO3−. The probe operates via a dual-response mechanism, exhibiting a visible color change and a transition from nonemissive to intense red fluorescence upon interaction with HSO3−. The detection mechanism involves a 1,4-nucleophilic addition reaction of HSO3− at the 4-position of the quinolinium unit, which bypasses the photoinduced electron-transfer fluorescence quenching pathway and activates the intramolecular charge transfer mechanism, thereby enhancing fluorescence emission. Practical applications of the RQB-R probe include rapid quantification of HSO3− levels in sugar samples and integration into smartphone-assisted detection platforms. This method demonstrates excellent biocompatibility and enables visualization of both exogenous and endogenous HSO3− within MCF-7 cells, with a specific focus on targeting mitochondria.

Spiroannulations of β-Ketothioamides with Bromoenals via Selective C-Michael Addition and S-Michael Addition-Triggered Cascade Reactions.

A spiroannulation reaction of β-ketothioamides with aromatic β-bromoenals and aromatic α-bromoenals via selective C-Michael addition and S-Michael addition-triggered cascade reactions has been developed. This protocol provides a novel and rapid approach for the synthesis of substituted spirothiopyran and spirothiophene derivatives under mild conditions with moderate to good yields and a broad substrate scope.

Fabrication of versatile and durable superhydrophobic cotton fabrics using PTA-Ala adhesive

In recent years, the preparation of functional textiles based on polyphenols adhesion has received extensive attention and research. However, polyphenols are prone to peroxidation during oxidative polymerization, which can compromise the interfacial adhesion of their monomers. Reintroducing reactive functional groups after oxidative polymerization of polyphenols may potentially compensate for the lost interfacial adhesion while increasing cohesion. In this paper, L-alanine (Ala) is introduced into poly (tannic acid) (PTA) solution to generate the PTA-Ala via Michael addition and Schiff base reaction. Original cotton fabrics are modified with PTA-Ala solution to enhance adhesion strength between the fabrics and subsequent functional modifiers. A silver nanowire network is then incorporated to increase the surface roughness through tannic acid reduction. Finally, polydimethylsiloxane is applied to reduce fabric surface energy, resulting in superhydrophobic multifunctional OH-PDMS/Ag/PTA-Ala/cotton fabrics. The finished cotton fabric exhibits a water contact angle of 166.7 ± 1.9° and a rolling angle of 5 ± 0.5°. Moreover, the fabric features diverse functionalities such as oil-water separation, photothermal conversion, antimicrobial properties, water collection, and anti-icing capabilities, alongside excellent durability and self-healing properties that extend its service life. This finished cotton fabric demonstrates promising applications in oil pollution control, outdoor clothing and medical protection, highlighting its broad across various industries.

Treatment of high-concentration semi-coke wastewater by phenolic condensation and persulfate oxidation

In this study, the combined process of phenolic condensation-persulfate(PS) advanced oxidation was adopted to treat semi-coking wastewater. Using the phenolic condensation method as a pretreatment unit to remove phenolic substances for the preparation of phenol-formaldehyde resins, and using an aerated/PS/pyrite oxidation system as a deep treatment unit to remove chemical oxygen demand (COD) and ammonia nitrogen (NH3-N) from the wastewater. Analysis and characterization of phenol-formaldehyde resin, organic compounds in wastewater, and pyrite using FT-IR, TG-DTG, GC-MS, and XPS techniques. The results showed that under the conditions of adding 1.8vt % formaldehyde, pH 10.5, reaction temperature 95 ℃ and reaction time 3 h, the removal rates of volatile phenol, COD and NH3-N in semi-coke wastewater were 97.54 %, 41.14 % and 56.50 %, and the yield of phenolic resin was 6.62 g/L. Subsequently, treated with an aerated/PS/pyrite system, the PS concentration 0.4 mol/L, the pyrite dosage 15 g/L, the pH 3, the temperature 65 ℃, and the aeration 3 h, the removal rates of COD and NH3-N are 99.20 % and 86.80 %. In the phenolic condensation process, phenolic substances in semi-coke wastewater generate phenoxy anions under the influence of OH-, which undergo addition reactions with formaldehyde to produce hydroxymethyl phenol. Hydroxymethyl phenol further undergoes condensation reactions with other phenolic substances and itself to form phenolic resin, while amide compounds are generated through reactions between ammonia nitrogen and carboxylic acid substances. In the aeration/PS/pyrite system, Fe2+ released from pyrite oxidation activates PS to produce SO4•− and O2•−. The contribution of free radical oxidation and decomposition of pollutants such as phenols, amides, and NH3-N in wastewater is 84.60 %. Specifically, SO4•− oxidation contributes 61.54 %, while O2•− accounts for 22.21 %. Amide compounds and phenolic substances in the wastewater are oxidized, leading to ring opening and chain scission, resulting in the formation of alkane compounds.

A terphenyl derivative-based colorimetric-fluorimetric probe for the detection of lysine and arginine and their bioimaging

Lysine (Lys) and arginine (Arg) play a crucial role in the human diets, medical diagnostics, and functional biomaterial synthesis. The imbalance of intake for these two amino acids causes various diseases. Although many analytical techniques have been reported for the detection of amino acids, there are still some issues such as the need for bulky instruments, professional operators, sensitivity to be improved, and real-time detection. Here, a novel colorimetric-fluorimetric probe based on a terphenyl derivative (TPT) has been synthesized for the precise detection of Lys and Arg. In the EtOH-H2O solution of TPT, the NH2 group at the chain end of Lys/Arg undergoes a nucleophilic addition reaction with CN groups of benzothiazole groups of the probe TPT, which breaks the initial long-conjugated system of the probe molecule. As a result, blue shifts can be observed for both UV–vis absorption spectra and fluorescence spectra, accompanying with color changes of the TPT solution. The UV–vis absorption peak of TPT solution shifts from ∼410 nm to ∼325 nm, and the solution color changes from light-yellow to colorless. The fluorescence emission shifts from ∼580 nm to ∼470 nm and the bright-yellow TPT solution changes to blue under the irradiation of 365 nm UV light. For colorimetric method, the limits of detection (LoD) are 0.82 μM and 0.90 μM for Lys and Arg, respectively. For fluorimetric method, they are 2.02 nM and 1.62 nM for Lys and Arg, respectively. In addition, TPT has good selectivity and anti-interference for Lys and Arg. The synthesized probe TPT has been successfully used for the precise detection of Lys and Arg in drugs and for fluorescence imaging of living cells. This work demonstrates that terphenyl-based derivatives are promising organic probes for the detection of Lys and Arg, providing a new way for designing other amino acids probes.

Drug-induced hypersensitivity syndrome due to phenytoin: Case report and review of the literature.

Drug hypersensitivity syndrome (DIHS) is a rare but potentially fatal adverse drug reaction characterized by fever, rash, and visceral organ damage, particularly affecting the liver. Early recognition and appropriate management are crucial to prevent serious complications. However, there is limited information on the clinical presentation and management of DIHS, especially in the context of antiepileptic drugs. This case report aims to highlight the importance of recognizing subtle clinical signs and symptoms of DIHS, which can be easily overlooked, particularly in the context of antiepileptic drug use. We report a case of a 15-year-old male patient who developed DIHS after being prescribed phenytoin sodium for epilepsy. The patient presented with symptoms of fever, sore throat, rash, jaundice, and liver dysfunction. Initially, the patient did not receive glucocorticoids and experienced additional reactions to cefoxitin and phosphatidylcholine, likely due to cross-reactivity. The diagnosis of DIHS was made based on the patient's clinical presentation, including fever, extensive rash, organ involvement, and hematological abnormalities. The temporal association with the use of phenytoin sodium, along with the exclusion of other causes of fever and rash, supported the diagnosis. Upon initiation of glucocorticoid therapy with dexamethasone, the patient's symptoms significantly improved. The rash and pruritus decreased, and laboratory values showed improvement, with a decrease in liver enzymes and normalization of white blood cell counts. The patient's fever resolved within 48 hours of starting corticosteroids, and there was no evidence of ongoing inflammation as indicated by a decrease in C-reactive protein levels. Furthermore, the patient's 30-month follow-up revealed no recurrence of rash, liver dysfunction, or organic damage, indicating the long-term effectiveness of the treatment administered. This case highlights the importance of recognizing the subtle clinical signs and symptoms of DIHS, especially in the context of antiepileptic drug use. It underscores the potential benefits of early initiation of glucocorticoid therapy in managing DIHS. The case also serves as a reminder of the potential for drug cross-reactivity in DIHS and the need for cautious drug selection during the acute phase of the syndrome.

Urushiol oligomer preparation and evaluations of their antibacterial, antioxidant, and thermal stability

There have been studies published on the composition and coating uses of raw lacquers following enzymatic oxidative polymerization. The change of urushiol’ thermal stability and biological activity following polymerization to create oligomer, however, has received little attention. This work using silica gel column chromatography to separate urushiol and urushiol oligomer from polymerized raw lacquer and assessed its antibacterial, antioxidant, and thermal stability in an effort to decrease the allergenicity of urushiol and increase its application. By using gel chromatography, the urushiol oligomer were discovered to be polymers with 2–5 degrees of polymerization. According to characterization results from techniques like UV, FT-IR, and 1H NMR, urushiol was converted into urushiol oligomer by addition reactions, and C–C coupling. The findings demonstrated that the urushiol oligomer’ IC50 values for scavenging DPPH and ABTS free radicals were 40.8 and 27.4 μg/mL, respectively, and that their minimum inhibitory concentrations against Staphylococcus aureus and Staphylococcus epidermidis were 250 and 125 μg/mL. The urushiol oligomer’s thermogravimetric differential curve peak temperature (461.8 °C) was higher than urushiol’s (239.5 °C), indicating that urushiol undergoes polymerization with enhanced thermal stability. The study’s findings establish a foundation for the use of polymerized urushiol and urushiol oligomer in applications including functional materials and additives.

Utilization of corn cob ash (CCA) to prepare geopolymer grout: Reaction mechanism, crack repair effectiveness and life cycle assessment

Corn cob ash (CCA) is a kind of agricultural solid waste produced by the burning of corn cob after removal of the corn kernels, which requires sustainable disposal routes. In order to utilize CCA and understand its role in geopolymer, CCA-amended geopolymer grout was prepared and effects of CCA on geopolymerization process and products were investigated in this study. With CCA included, there was less C-S-H/C-A-S-H gel and more calcite, also portlandite generated. Two extra weak exothermic peaks were observed for CCA-amended geopolymer with optimal mix proportion (CCA20A6), probably due to additional reactions induced by CCA, also verified by the disappearance of syngenite. Following application of CCA20A6 to repair cracks, compressive strength and ultrasonic pulse velocity (UPV) of the repaired composites were improved, and no cracking was observed at the bonding interface, verifying successful repair. Based on life cycle assessment in cradle-to-site boundary, the total embodied energy (EE) and global warming potential (GWP) of CCA20A6 were decreased by 7.8% and 15.5%, respectively, compared to non-CCA geopolymer. Considering performance of samples, the addition of CCA would lead to an about 30% decrease in economic index. In conclusion, CCA could play a role as a precursor due to soluble Si, Al, and Ca components, and also as an activator due to its intrinsic alkalinity, which makes CCA-amended geopolymer to be an eco-friendly grouting material with better performance as well as lower costs.

A novel dialdehyde cellulose-based colorimetric and turn-on fluorescent probe for H2S detection and its application in red wine

Hydrogen sulfide (H2S) is considered one of the most important gaseous transmitters in the metabolic system, and the abnormal concentration of H2S is associated with a variety of diseases. Up to now, it is still a challenge to develop a portable assay for H2S even though the research about the detection of H2S is booming. Herein, a novel bifunctional dialdehyde-cellulose fluorescent probe DAC-DPD was prepared with high selectivity and sensitivity to H2S with colorimetric and fluorescent “turn-on” characteristics, and the limit of detection (LOD) of DAC-DPD for H2S was 0.831 μM. The sensing mechanism of DAC-DPD's to H2S was a Michael addition reaction confirmed by HRMS, 1H NMR and density-functional theory (DFT) calculations. DAC-DPD can be used to detect H2S in red wine samples. In Addition, the prepared DAC-DPD embedded fluorescent membrane can be used as a reliable sensing platform for rapid detection of H2S. It provided a convenient and rapid detection material, simplifying the detection process of H2S, which is of great significance for the development of cellulose-based fluorescent smart material.

Kinetic and catalytic mechanism of the methionine-derived glucosinolate biosynthesis enzyme methylthioalkylmalate synthase

In Brassica plants, methionine-derived aliphatic glucosinolates are chemically diverse natural products that serve as plant defense compounds, as well as molecules with dietary health-promoting effects. During their biosynthesis, methylthioalkylmalate synthase (MAMS) catalyzes the elongation reaction of the aliphatic chain. The MAMS catalyzed condensation of 4-methylthio-2-oxobutanoic acid (4-MTOB) and acetyl-CoA generates a 2-malate derivative that either enters the pathway for synthesis of C3-glucosinolates or undergoes additional extension reactions, which lead to C4- to C9-glucosinolates. Recent determination of the x-ray crystal structure of MAMS from Brassica juncea (Indian mustard) provided insight on the molecular evolution of MAMS, especially substrate specificity changes, from the leucine biosynthesis enzyme α-isopropylmalate synthase (IPMS) but left details of the reaction mechanism unanswered. Here we use the B. juncea MAMS2A (BjMAMS2A) isoform to analyze the kinetic and catalytic mechanism of this enzyme. Initial velocity studies indicate that MAMS follows an ordered bi bi kinetic mechanism, which based on the x-ray crystal structure, involves binding of 4-MTOB followed by acetyl-CoA. Examination of the pH-dependence of kcat and kcat/Km are consistent with acid/base catalysis. Site-directed mutagenesis of three residues originally proposed to function in the reaction mechanism - Arg89 (R89A, R89K, R89Q), Glu227 (E227A, E227D, E227Q), and His388 (H388A, H388N, H388Q, H388D, and H388E) - showed that only two mutants (E227Q and H388N) retained activity. Based on available structural and biochemical data, a revised reaction mechanism for MAMS-catalyzed elongation of methionine-derived aliphatic glucosinolates is proposed, which is likely also conserved in IPMS from leucine biosynthesis in plants and microbes.

Unveiling the Structural Complexity of Lithium Organozinc Alkoxo Clusters and their Applications to Enantioselective Michael Addition Reactions

We report three novel lithium zincate alkoxo clusters, which can be accessed through a convenient co‐complexation reaction of the corresponding dialkylzinc derivatives with lithium alkoxides of the formula [LiO(CH2)2N(CH3)2], or via a deprotonation process mediated by the higher‐order zincate Li2ZnEt4 and dimethylethanolamine. These complexes have been isolated as colourless crystalline solids and characterised by multinuclear magnetic resonance spectroscopy, elemental and single‐crystal X‐ray diffraction analysis. XRD analysis of the crystal structures, combined with 1H DOSY NMR experiments, was crucial for understanding the chemistry behind these complexes. Furthermore, complexes obtained by mixing ZnEt2 with a chiral nonracemic lithium alkoxide generated from (1R,2S)‐N‐methylephedrine have been explored in promoting an enantioselective Michael addition reaction towards trans‐β‐nitrostyrene, with the corresponding nitroalkane isolated in up to 37.3% enantiomeric excess.

Sustainable rewritable paper based on photoresponsive tungsten oxide quantum dots for anti-counterfeiting and waterproofing

Ink-free printing using photochromic paper has emerged as a promising technology for information recording, transmission, and secure interaction applications. Tungsten oxide quantum dots (WO3 QDs), with their rapid UV response, excellent photochemical stability, and outstanding fatigue resistance, exhibit significant potential as an ink-free medium in the construction of sustainable rewritable paper. However, challenges such as low binding force, poor stability, and weak scalability limit the development of reversible photochromic paper based on WO3. In this study, a novel sustainable rewritable paper based on a scalable strategy of covalent modification and hydrophobic layer protection has been reported. Specifically, cellulose papers modified with silane coupling agent were directly grafted with amino-modified WO3 QDs by covalent bonding through the addition reaction between epoxy and amine groups. Subsequently, the sustainable rewritable paper was obtained by the deposition of hydrophobic layer of polydimethylsiloxane (PDMS) via a dip-coating method. The rewritable paper exhibits exceptional properties, including high color contrast, extended color-retention (over 21 days), good rewritability (20 cycles) and excellent resistance to water or stains. Based on ink-free writing technology, the photo-responsive rewritable papers were utilized for anti-counterfeiting and encryption or decryption, demonstrating their great potential for information recording, storage, and security protection.

Recent Routes in Synthesis and Biological Activity of Pyrimido[4,5-b] Quinoline Derivatives: A Review (Part II)

The synthesis of organic molecules has been a tremendous and rapid advance in the recent decade to obtain high biological and pharmacological activities. In this review, the organic synthesis of pyrimido[4,5-b]quinoline derivatives is considered an alternative method to traditional procedures for treating many diseases that affect humans. Also, by transferring electrons, stereoselective syntheses occur via organic reactions in various unnatural and natural conditions at room temperature and normal pressure. We found that the structure of pyrimido[4,5-b]quinoline derivatives was formed by substrates, bases, electrophiles, and low-level and highly stable reagents that can be broadly applied to synthesize more heterocycles. These reagents include: 2- nitrobenzaldehyde; 3-(benzyloxy)-4-methoxy-2-nitrobenzaldehyde; 4,5-dimethoxy-2- nitrobenzaldehyde; 2-aminobenzaldehyde; 2-aminoquinoline-3-carboxamide; 2-chloroquinoline3-carbaldehyde; 2-bromobenzaldehyde; 2-chloroquinoline-3-carbonitrile; 2-chloroquinoline-3- carboxylic acid; aniline; phenyl-methanamine; amino-quinoline-3-carboxylic acid /aminoquinoline-carbonitrile; amino-6,7-dimethoxy-quinoline-3-carbonitrile; amino-oxolo [4,5- g]quinolin-carboxamide; 3-(aminomethyl) quinolin-2-amine; 4-aminobenzo[d][1,3] dioxole-5- carbaldehyde; thiourea; ethyl 3-oxo-butanoate; 2-cyano-acetamide; 2-(bis (methylthio) methylene) malononitrile; ethyl 3,3-diamino-2-cyanoacrylate; naphthalene-1,4-dione; and N-carbamoyl-2- cyanoacetamide derivatives. The prepared pyrimido[4,5-b]quinoline derivatives were described through means of the following chemical reactivity: alkylation, bromination, chlorination, cyclocondensation, cyclization, acylation, oxidation-reduction, dehydration, addition reaction and Vilsmeier-Haack reaction (Vilsmeier reagent).

Carbodiphosphorane-Activated Distibene and Dibismuthene Dications.

Low-valent antimony and bismuth have emerged as novel platforms for achieving reversible small-molecule activation at main-group metals. Although various examples of oxidative addition reactions at monomeric Sb(I) and Bi(I) have been reported, the chemistry of the heavy group 15 Sb(I)═Sb(I)/Bi(I)═Bi(I) double bonds toward small molecules remains largely unexplored. In this study, we present a straightforward synthesis of distibene and dibismuthene dications coordinated with a neutral carbodiphosphorane (CDP) ligand. The nonbonding interactions between the occupied p-orbital at the CDP ligand and the π-bonding orbital of the Sb═Sb/Bi═Bi bonds yield compounds with exceptionally small HOMO-LUMO gaps. In addition, the reduction of steric hindrance compared to known neutral derivatives stabilized with bulky aryl groups allows for better accessibility of the double bonds. This high reactivity is demonstrated in the oxidative addition of distibene to diphenyldisulfide as well as in [2+2] cycloadditions to alkynes. Additionally, the Sb═Sb bond reversibly adds to 2,3-dimethylbutadiene in a [4+2] cycloaddition reaction.